Treatment of drilling fluids



" variation of the colloidal Patented no 9, 1943 UNITED STATES PATENT OFFICE Truman 3. Wayne, Houston, Tex.

No Drawing. Application August 31, 1939,

' Serial No. 292,887

10 Claims.-

This invention relates to mudeladen or drilling fluids and particularly to the treatment of drilling fluids used in rotary drilling for petroleum, natural gas, and sulfur. This application, as to common subject matter, is a continuation-inpart of my application, Serial No. 164,528, flled September 18, 1937, issued October 8, 1940, as

U. S. Patent 2,216,865.

The fluid employed for rotary drilling operations-may be made from the natural clay which occurs at the location or may be synthetically compoundedfrom the clay and mud bases of commerce, including bentonite and beidellite. Such fluids may also contain a heavy substance such as barytes, iron oxide, or the like, for increasing the speciflc gravity of the fluid.

Such fluids as are synthetically compounded may be controlled as to viscosity by a proper content, but when the cuttings from the bore hole become entrained in the fluid, its composition has changed, and furto permit the cuttings to settle out and render the fluid of such character that it will not be susceptible to gas cutting. With fluids which are compounded with the clay at the location, it is obvious that such control is more dimcult.

Furthermore, it is sometimes desirable to reduce a a theviscosity of drilling fluids initially.

It is an object of the present invention, generally stated, to provide a process and agent "for the treatment or degelling of mu'd-laden or drilling fluids in order to control the viscosity and thixotropic properties thereof.

Another object of the inventionis to provide a process and agent for treating such fluids where- .by theproperties of the hydrated clay colloids are modified and the viscosity of the fluid reduced.

A further object of the invention is to provide a mud-laden or drilling fluid and the process of making it in-which the properties of the colloidal matter in the fluid are substantially modified and rendered suitable for rotary drilling purposes.

A more specific o'bjectof this invention is to providea process and-agent for the treatment of mud-laden or drilling fluids from a class of chemical reagents, and a treatment wherein a member of said class of chemical reagents is 50 used, and a drilling fluid which has been suitably modifled by said treatment, as will hereinafter be described.

Other objects will become apparent to those skilled in the art when the following description 55 is read.

In accordance with the present invention, generally stated, a mud-laden fluid such as that employed in the rotary drilling of oil wells may be treated with a chemical agent which, upon 60 ther control is often necessary in order to maintain the desired viscosity but at the same time reaction with certain constituents of the fluid, modifies the colloidal properties of the'colloidal matter in the fluid. More specifically, in accordance with the present inventioma degellingaction on the mud laden or drilling fluid is produced by a class of chemical substances, dispersible-in-water, which may be generally described as ester-like bodies of resinous or fused nature produced by the reaction of hydroxy organic bodies with an acidic body derived from the class comprisingsuitable acid-forming oxides of elements preferably selected from group V of the periodic system of elements. Thismay be accomplished by treatment with chemicals so selected that the reaction which accomplishes the change produces a substantially irreversible reduction in the hydration or hydration capacity of the gelatinous, colloidal fraction of the'drilling fluid. This results in a desirable modification of the gel strength and the 'thixotropic properties, as wellas a substantial viscosity reduction. Other benefits such as better wall building, an impervious fllm' on the bore-hole surfaces which prevents water inflltrationinto the formations, release of occluded gas and the prevention of gas-cutting, are also obtained. This action has :been descriptively referred to herein, and in my copending application, Serial No. 164,528, as a degelling action.

There are considerable"variations in the properties'of the acid-forming oxides of the elements comprising group V. Owing to their relative reactivity, clieapness, and availability, ester-like bodies prepared from a hydroxyorganic body and the acids, anhydrides, or acid salts offphosphorus, vanadium, and arsenic are preferred. A number of suitable chemical bodies, produced by such reactions are hereinafter enumerated, but it will be understood that other suitable substances are contemplated.

Many of the Oxy-acids derived from the. acid-v forming oxides of elements comprising group V exist in the ortho, meta, and pyro forms, depending upon the degree of hydration of the acidic oxide, or, conversely, on the degree of dehydraq tion if prepared from an ortho acid or salt. In addition to these various forms, it is contemplated that polymeric forms prepared by heating the acids or acid salts are useful in my process. Amorphous "glasses prepared by .fusion and/or dehydration of acid salts are highly suitable for my purpose, provided they still contain reactivegroups or bonds which allow them to combine chemically with one or more hydroxyl groups of hydroxy organic bodies. The various polyphosphate fusions are the best known products belonging to this class, but various others derivable from acid arsenate or vanadate complexes are also useful. In the majority of cases it is preferable to prepare these complexes by polymerization of hydr'oxy-anthraquinones,

.a combination of droxyl group, amino group,

fraction and to the the reaction products prepared from pyro acids or acid salts body. However, the

simpler ortho, meta, or and the hydroxy organic poly-derivative of the acid-forming oxide may, first be'prepared, and then reacted with droxy organic body.

The hydroxy organic used in preparing my improved reagents group comprising tannins, sugars, lulose, gums, lignin's, humins, hydroxy organic acids of the aliphatic, alicyclic, or aromatic series,

kylolamines, and other may be selected from the 1 starches, celp lyh coho s. 1 hydroxy organic bodiesv capable of undergoing esteriflcation reactions with a reactive derivative of an acidic oxide;

Usually the tannins, and hydroxy. aromatic organic acids are preferred for reasons-of availability and'cost. 1 1 i In the preparation of myimproved reagents, reaction conditions must be chosen which wllleffect esteriflcatiom, addition or etheriflcation, or

, these reactions, so that chemical combination occurs between the acidic function of the acidic oxide derivative, and the hyor other combining group of, the hydroxy organic body. 'Iheterm ffester-like" has beenused herein to describe'the reaction products so produced, regardless of whether chemical combination .has been. produced solely by esterification, or not. Since poly-. merization to the higher semi-resinous forms is usually produced when these reactions are conducted abovev the melting point of the hydroxy organic body, union through the splitting off of Water from hydroxyl groups often occurs. can not be strictly considered as esterification; rather, it is atype of etherification, butjsince the acidic oxide derivative has acted as an acidic body in itschemical reactions with the hydroxy organic body, the. final. products are herein describedas ester-like bodies.

The colloidal fractions of bentonite, as wellfas those of various claysiobtained, from wide y different'locations, are 'qulte. similar in their composition withrespectto silica, alumina, and iron, the main deviation only 4 centof the average of each of thesesubstances. The diiierences in properties exhibited by mudladen or drilling fluids prepared from clays and clayey materials obtained. from various sources are largely due to varying proportions of calcium and/or magnesium present in the colloidal larger proportion of noncolloidal inert material contained in the same clayey suspension. In all cases these gel sub stancesvare complex hydrous silicates containing considerable proportions of alumina and, in fact, may be classed either as hydrous alumino-silicates or in some instances hydrous silico-aluminates. Such substances invariably contain appreciable quantitiesof calcium and/or magnesium in their composition and it has been observedtha't the corresponding sodium or potassium compound does not possessthe same degree of gelatinous properties and the" accompanying high viscosity that isassociated with the corresponding alkaline-earth bearing hydrous silicates.

In order to illustrate the principles of my invention, a number of specific'examplesa're hereinaft'er given. However, it should be distinctly understood that I donot confine myself to the specific treating agents, drilling fluid compositions, or proportions hereinafter disclosed, as it should be understood by those skilled in the art that variations from these disclosures do not de part from the principles and spirit of my invention which is directed in a general way to the use of polymerized ester-like bodies of resinous or ,fusednature infthe degelling and controlling of viscosity or mud-laden ordrilling fluids.

The tests described in the following examples were conducted on well drilling fluids prepared largely fromwyoming bentonltes and water so as to have a maximum contentof the hydrous aluminum silicates which arev reacted upon in the manner herein described. Drilling fluids prepared from natural clays and shales usually encountered during drilling operations are similarlyacted upon, since in all cases the colloidal fractions of such materials are quite similar in mpositionand properties'to the purer colloidal gel-forming materiahbentonite. Tests were made using this degellingof product in the an8% aqueous bentonite In all cases aqueous solutions of the treating asent' were dded to 200 mLsamples oi the drillmg fluid in the proportion specified. agitated thoroughly, and tested in a Stormer viscosimeter at 60.0 R. P. M.,,and at atemperature of 20-390. 3-"EXAKPLI1' I 300 parts of anhydrous quebracho extracted:- taining approximately l0%' tannins were care fully mixed, with 140 parts of phosphorous .pentoxme in a rapidly. shaken glass vessel equipped with a cooling jacket; The reaction was started by warming slightly, and was thencontrolled by means of coolingwater to prevent decomposition.

After the exothermic reactionhadceased, the air was exhausted from the vessel by of a vacuum'pump, andthe mass was heatedin vacuo to'the fusion, point. The .water vapor formedduring fusionwas' continuously exhausted from the vessel. The temperature was then lowered; somewhat, the vacuumbroken', fused mas's poured out to'cool to a hard,.brlttle' mass which'was fullys'oluble inwater. Reailts. obtainedfromtests on an 8% Wyoming. bentonite suspension are given injTable I.

l ExAmrLs2 2o parts by weight of anhydrous chestnut ex tract containing approximately tannins were added t' 20' parts of melted ammonium imido diphosphoric acid,

' I NHiQ i o and the mass wasstirred vigorously. to mm porate the tannin into mixture was then placed in a vessel and heated at 200 C. in vacuo to meltand'fuse' the mass to a homogeneous clear melt. The vacuum was .used to reduce oxidationof the organicbodyand to facilitate removal of water formed during'the reactions. However, the same reactions could be conducted in an atmosphere of inert gas. .Upon cooling, '3. hard, brittle glass was formed which was solublein water. Results obtained from tests with this product on an 8% 'Wyoming bentonite suspension are given in Table I.

The exact structure of the above product has not been accurately determined. Howeven'it is known that ammonium imido diphosphoric acid readily condenses to higherv formsupon fusion.

the molten mass. The

andin view of its acidic propertiesand the plurality of reactive groups on the tannin body, a

complex of 'high'molecular weight results which is considerably more eflicientas, a degelling agent than equivalent proportions of either the diphosphoric acid complexor the tannin, or mechanical admixtures of the two substances.

EXAMPLE 3 20 parts by weight of anhydrous mono-ammonium dihydrogen orthophosphate, NHQHaPO'i,

were melted at approximately 300 C. Consider- "able ammonia was evolved together with water vapor. To the molten fusion product were quickly added 20 parts of anhydrous chestnut tannin extract and the mass was vigorously stirred until it solidified. It was then heated in vacuo to 200 C. to fuse the product into a clear melt, after which it was cooled as a dark-colored, clear, glass.

Tests with this .product, which greatly resembled the product of Example 2, on 8% Wyoming bentonite suspensions .are reported in Table I.

EXAMPLE 4 11.5 parts by weight of NH4H2PO4 were melted as described in Example 3, and 15 parts of tartaric 'acid were rapidly stirred into the molten mass.

The mass was then fused in vacuo in the manner previously described. Tests on 8% Wyoming bentonite suspensions are reported in Table I.

EXAMPLE 5 11.5 parts by weight-of NH4H2PO4 were melted and fused with 9.5 g. of technical gallic acid in the manner previously described. Tests on 8% Wyoming bentonite suspensions are reported in Table I.

'EXAMPLE 6 13.5 parts by weight of anhydrous monoammonium dihydrogen vanadate were fused in the manner previously'described, and 20 parts of anhydrous chestnut extract were added. The

mass was heated to the melting and fusion point in a. glass retort connected to a vacuum pump for maintaining a vacuum of 29 inches of mercury. The glass so formed was used in the treatment of an 8%Wyoming bentonite suspension. Results are reported in Table I.

EXAMPLE '7 1 15.9 parts by weight of mono-ammonium dihydrogen orthoarsenate were fused and mixed with 20. parts of chestnut tannin extract, and fused in vacuoas previously described. The organic arsenate glass was used in the treatment of an 8% Wyoming bentonite suspension. Results are reported in Table I.

Table I Grams reagent per 100 ml. of drilling fluid Material example No.

Original fluid (no treatment) 38 38 38 3B 38 1 25 21 17 15 10 2;; 27 21 17 13 25 21 17 .15 13 4 25 21. 17 15 13 5 25 21 17 15 11 6 25 21 17 13 11 7 27 25 21 19 15 The values listed are in centipoises (Stormer).

The similarity in results obtained from the use of organic polyphosphate complexes whose organic radicals were derived from different sources is immediately apparent. This similarity in results, all being a matter of degree, has also been noted as characteristic of the various inorganic polymeric derivatives of polybasic phosphoric acid compounds described in my copencling application, Serial No 163,612, filed September 13, 1937. Evidently, the polyphosphoric acidradical is specific in its action on the gel-forming colloidal bodies in well-drilling fluids, whether in strictly inorganic form or in organic combinati ns. The latter, however, as exemplified inthe present application, represent an improvement in the art due to their somewhat higher effectivenes. as degelling agents.

A particular advantage of the ester-like treating agents herein disclosed is their stability in drilling muds which-have acquired high temper atures when circulated in the bore hole. Ternperatures considerably above the boiling point have been recorded in certain instances. When using the strictly inorganic polyphosphates under such conditions, reversion to the ortho forms may occur to a. considerable degree, and this often results in an undesirable increase in the viscosity of the drilling fluids under the temperature conditions above described. These organic phosphates resist these changes and maintain their efliciencies for much longer periods at elevated temperatures.

The organic vanadates and arsenates, likewise derivatives of acidic oxides and an organic hydroxy body, are also of value for this purpose, as

it is shown in Table I.

.While in the preceding examples either ths highly reactive acids or anhydrides, or the more easily fusible ammonium derivatives of acidic oxides have been used to facilitate preparation of these ester-like bodies at temperatures low enough to prevent substantial decomposition and carbonizing of the hydroxy organic body, it will be understood by those skilled in the art that other acidic oxide derivatives of higher melting and fusion points, such as the corresponding alkali-metal salts are also contemplated. Also that other hydroxy organic bodies with higher melting and/0r decomposition points are also contemplated, especially when the inorganic material possesses a higher melting point. However, for

convenient preparation ,of suitable ester-like products I prefer the acidic oxide derivatives which may be reacted at lower temperatures with a wide variety of hydroxy organic bodies whose melting or boiling points range between 260 C.

It should also be understood that the fusion method of preparation above described represents only one convenient and practicable method of preparing such products. They may also be prepared by reactions in solution or in'the presence of an inert vehicle or medium wherein the reacting materials are brought into contact. Various methods of conducting such reactions are known to the skilled organic chemist, and the method of preparation is immaterial. The preceding description relating to preparation of these esterlike organic bodies is purely illustrative.

The above described products may be usedalone in the degelling of drilling muds, or may be used in connection with lyophile colloids, buffer substances, alkalies, phosphates, borates, or other substances now in use for this purpose.

The preceding examples exemplify the use of my improved degelling agents on a normal mudladen drilling fluid prepared in the usual manner from natural or synthetic mud-making mateexcess bentonite or other material added, and

thusallows' larger proportions of gel-forming material to water than normally can be incorporated 'in' the drilling fluid. For instance,

whereina normal 8 per cent suspension of bentonite in water may have a viscosity of 38' centipoises in the Stormer viscosimeter 'at '600 R. P. M., if the drilling fluidcoritains as much as2 per cent of the treating agent, very much larger quantities of bentonite 7 may be incorporated without unduly increasing the viscosity. In fact, fluid muds may thus be prepared from 'bentonite which approximate the solids composition of muds prepared from natural sources.

"It is likewise'obvious that muds which have become contaminated with cementgcalcareous shales,:and/or other sources of polyvaient metal compounds which have produced abnormal viscosities, will require heavier treatment withmy improved treating agent to' produce normal vis-v cosities for muds so contaminated.

' While in'the foregoing, theories are advanced,

these are put forward to facilitate the'understanding of the objects and purposes of this invention; it is to be understood, however, that this invention is not dependent upon or limited to any theory put forward.

' What is claimed is:

'1. Theprocess of reducing-and controlling the gelation and viscosity characteristics of an aqueous mud-laden well-drilling fluid comprising adding thereto a small percentage of a dispersible-in-water compound, which compound is the condensation product resulting from the condensation of a hydroxy organic body and a substance selected from the group consisting of the [acidic oxides and acidic oxide derivatives of the elements of group V of the periodic table. 7

2. The process of reducing and controlling the gelation and viscosity characteristics of an aqueous mud-laden well-drilling fluid comprising adding thereto a small percentage of a dispersible-inwater fusion product, which product is the condensation product resulting from the fusion and condensation of a hydroxy organic body and a substance selected from the-group consisting of the acidic oxides and acidic oxide derivatives of the elements of groupV of the periodic table.

3'. The process of reducing and controlling the gelation and viscosity characteristics of an aqueous mud-laden well-drilling fluid comprising adding thereto a small percentage, of a dispersible-in-wate'r' polymerized fusion product, which product is the condensation product resulting from the fusion and condensation of a hydroxy organic body and a substance selected from the group consisting of the acidicoxides and acidic oxide derivatives of the elements of group V of the periodic table.

4. An aqueous mud-laden well-drilling fluid containing a relatively small percentage of a dispersible-in-waterfusion pro uct; which roduct is the product resulting from the fusion'and condensation of ,a hydroxy organic body and a substance selected from the group consisting of the acidic oxides and acidic oxide derivatives of the elements ofgroup v of the periodic table.

5. An aqueous mud-laden well-drilling fluid containing a relatively small percentage of a dispersible-in-water polymerized fusion product.

which product is the condensation product resuiting from the condensation of a hydroxy or ganic body and a, substance selected from-tho group consisting of the acidic oxides and acidic oxide derivatives of the elements of group V of the periodic table. v

6. An aqueous mud-laden well-drilling fluid containing a relatively small percentage ofa div persible-in-iwater compound, which compound is -the.condensation product resulting fromthe condensation of ahydroxy organic body and a substance seiected'from the group consistingfof the acidic oxides and acidic oxide derivatives of the elements of group V. of the periodic table.

7. The process for treating an aqueous mudvladen well-drilling fluid comprising addingthereto a small percentage of a dispersiblo in-water compound, which compound is the condensation product resulting from at least one typeof condensation reaction selected from. thegroup-oonsisting of esteriflcation, etheriflcation, polymerization and combinations thereof, involving a hydroxy organic body and a substance-selected from the group consisting of the acidic oxides and acidic oxide derivatives ofthe elements of group V of the periodic table. 1

8. The process for treating an laden well-drilling fluid comprising adding thereto a small percentage of adispersible-in-water compound, which compound is the condensation product resulting from at least one type of oon-- sisting of esteriflcation,

densation reaction selectedfromthegroup cone ethellflcatlonv W merization andcombinations thereof, involving a hydroxy organic body andan acidic compound selected from the group consisting of acid-forming vanadium oxides and acidicderivatives of said oxides.

9. The process of treating an aqueous wellpercentage of a dispersible-in-water compound, which compound is the condensatiorf product resulting from at least one type of condensation reaction selected from the group' consisting of an esteriflcation, etheriflcation, polymerization and combinations thereof, involving an, organic hydroxy body and an acidic compound selected from the group consisting of acid-forming arsenic oxides and acidic derivatives of said oxides.

10. The process for treating an aqueous mudladen well-drilling fluid comprising, adding thereto a small percentage of a dispersible-in-water compound, which compound is the condensation product resulting from at least one type of condensation reaction selected from the group consisting of. an esteriflcation, etheriflcatiori, polymerization and combinations thereof, involving.

time; mod- 

